There is known a LCD device including a plurality of sub-pixels in each pixel of the LCD device. Examples of such a LCD device include a transflective LCD device wherein each pixel includes a sub-pixel corresponding to a transmissive area and a sub-pixel corresponding to a reflective area. In the transflective LCD device, if a lateral electric field mode, such as an IPS (in-plane-switching) mode or FFS (fringe-field-switching) mode is adopted, a black-white inversion problem is known, wherein display of a dark state and display of a bright state are reversed between the transmissive area and the reflective area such that the transmissive area assumes a normally black mode and the reflective area assumes a normally white mode, as described in Patent Publication JP-2003-344837A, for example. In a typical longitudinal (vertical alignment) mode, the problem of black-white inversion is optically solved by inserting a λ/4 film. However, in the lateral electric field mode, the technique of inserting the λ/4 film cannot be adopted.
Patent Publication JP-2007-041572A describes a technique for solving the above black-white inversion problem without inserting a λ/4 film. In the technique of this publication, the black-white inversion problem is solved in a specific drive scheme by applying voltages that provide reversed gray-scale levels to the reflective area and the transmissive area. FIG. 15 shows the circuit configuration of a pixel in the LCD device described in JP-2007-041572A. Each pixel 50 includes a first common electrode 53 corresponding to the reflective area 51, second common electrode 54 corresponding to the transmissive area 52, and pixel electrodes 55 and 56 in the reflective area 51 and the transmissive area 52, respectively, to which a common data signal is applied. The liquid crystal (LC) layer in the reflective area 51 is driven by the electric field generated between the pixel electrode 55 and the first common electrode 53, whereas the LC layer in the transmissive area 52 is driven by the electric field generated between the pixel electrode 56 and the second common electrode 54.
In the technique of JP-2007-041572A, the signal applied to the first common electrode 53 and the signal applied to the second common electrode 54 are reversed. For example, when 5V is applied to the pixel electrodes 55 and 56, 0V and 5V are applied to the first common electrode 53 and the second common electrode 54, respectively. In this configuration, 5V is applied to the LC layer in the reflective area 51, whereas 0V is applied to the LC layer in the transmissive area 52. Thus, LC molecules in the LC layer are turned only in the reflective area 51, whereby the problem of black-white inversion is solved.
JP-2007-041572A describes the relationship of potential inversion between the first common-electrode signal and the second common-electrode signal in each pixel; however, the publication is silent to the relationship in the common-electrode signal between adjacent rows of the pixels in the whole display area of the LCD device. In addition, there is no teaching as to the technique for generating the common-electrode signal and as to the electric connection in the display area.